Exhaust driven turbochargers include a rotating shaft carrying a turbine wheel and a compressor wheel where the shaft is typically rotatably supported within a center housing by one or more lubricated bearings (e.g., oil lubricated). During operation, exhaust from an internal combustion engine drives a turbocharger's turbine wheel, which, in turn, drives the compressor wheel to boost charge air to the internal combustion engine.
During operation, a turbocharger's rotating assembly may reach rotational speeds in excess of 100,000 rpm. To handle such high speeds, a turbocharger's center housing rotating assembly (CHRA) requires balance and adequate lubrication. Factors such as noise, vibration and harshness (NVH), as well as efficiency, are often interrelated and must be within acceptable limits. As an example of interrelatedness, vibration can generate noise and reduce efficiency. Further, under dynamic conditions, such as an increase in exhaust flow, axial thrust forces can cause contact between various CHRA components. Contact can cause wear, which, in turn, can alter balance, leading to increased noise, vibration, etc., and reduced efficiency.
Various technologies described herein pertain to bearing assemblies, where, for example, one or more components can provide for increased damping and, consequently, reduced CHRA vibration.